1. Technical Field
The present invention relates to lens modules, particularly to a lens module that is capable of preventing stress occurring on the optical components of the lens module, and a method for assembling the lens module.
2. Description of Related Art
Nowadays, camera modules are being combined with various portable electronic devices such as mobile phones, personal digital assistants (PDAs), and laptop computers to be increasingly multi-functional.
The lens module is a very important component of the camera module. Generally, the lens module includes a holder, a barrel, an image sensor, and a number of optical components such as optical lenses and filters received in the barrel. The barrel is partially received in the holder. The image sensor is generally held inside the holder, and disposed at a bottom of the holder or at the end of the barrel received in the holder. The optical components are coupled with the image sensor so as to capture images. A coaxial alignment of the optical axes of the optical components is the key factor for having a good image quality.
However, during using the lens module to capture images, the image sensor works and generates heat. The generated heat causes a temperature gradient distribution in the lens module, which further causes each of the optical components to generate different thermal stresses and an internal stress therein. Due to the thermal stress and the internal stress, the optical components tilts and moves. The optical axes of the optical components cannot maintain the coaxial alignment. Therefore, the lens module has a poor optical modulation function (MTF) and a poor image quality.
What is needed, therefore, is a lens module that is capable of preventing stress occurring on the optical components of the lens module. What is also needed, therefore, is a method for assembling the lens module.